This is a tough one, and I'll not lie, the first time I did it I finished with one command center flying away from the ruins of my base while the timer ticked down the last seconds. Everything here assumes that you know how to make a base defense fast, and that you know how to maintain it. Otherwise, you'll struggle just to complete this mission on hard difficulty.

The easiest way to perform this Achievement is to kill one base twice. The least defended zerg base is in the top-left corner.

Hit the base early, but bring a solid group, at least 10 marines and four medics, though I'd say double that to be sure. Stay close to the cliff on the right side going in so that you don't have to fight all the defense at once. Don't rush in, just hold there until you have nothing left to shoot and move forward. Notice there are two hatcheries here. Kill them, then return to defending your base.

Nearing the end of the mission (for me it was with a minute and a half to go that I noticed it), the base you trashed will start respawning two new hatcheries, but no defenses. Park some boys up there (safe from the waves of zerg funny enough) and just wait until the hatcheries finish morphing, then blast 'em.

This Achievement doesn't require you to beat the mission, so if you can kill the hatcheries but your base is getting trashed, just nail the hatcheries and reload.

The first thing you need to do is make a strong defense for your base. Start pumping out marines and medics as soon as you can. You can make a third barracks if you want. I would recommend rescuing the three terran groups isolated outside of your base, simply because they are free troops and will help you in completing this mission. After you have about 20 marines and 10 medics, start making your way to the left side of the map. There are three hatcheries there. When you attack, focus firing on the spine crawlers because they are the most dangerous for your marines and then just pick out other attack enemies. After that, just clean up the base and move to the top-left corner. There are two hatcheries there and you only need to destroy one to finish the Achievement. For now, your base should be making more marines and medics, so let them join the fight if you can and do the same thing as with the left base. Focus on spine crawlers when you get in range and then other enemies. After you destroy that hatchery, just come back and defend your base. Nydus worm should start popping in your base soon, if they haven't already.